Lubricant



Patented July 30, 1940 UNITED STA'EES PATENT OFFICE aaaignors to Standard Oil Company, Chicago, 111., a corporaflon oi Indiana No Drawing.

1938, Serial 16 Claims.

This invention relates to lubricants and, in

particular, to addition agents imparting to lubricants improved properties. This application is a division of our oo-pending application Ser. No.

108,832 filed November 2, 1936, now issued as Patent No. 2,160,880 of due 6, 1939.

Our invention has particular utility in preventing and/or inhibiting the corrosion of "hard metal alloy bearings such as copper-lead, cadmium-nickeLand cadmimn-silver bearings which,

to a large extent, have replaced soft metal bearings such as babbitt metal in the trend toward internal combustion angina having high compression ratios and having increased acceleration and increased speed characteristics. The use of the hard me bearings has created lubrication and corrosion problems, particularly in connection with "highly refined oils, some of which may be very corrosive to the hard met 29 bearings.

By highly refined lubricating oils we mean viscous oils which have a minimum viscosity in therangeoiS.A.E. oilsandwhichhavebeen subjected to such refining processes such as, for 7 example, solvent extraction, that the city of the oil is markedly increased. It has been found that highly refined mhricatlng oils cause corrosion to alloy bearings of the cadmium-silver type to the extent of 5 mgJcm. and even greater when such bearings are submerged for 25 hours orlessinanairagitatedoilwhichhasbeen preoxidized at about 340 F. for 25 to 50 hours. The motor oils may be highly refined lubricatin oils as such or mixtures of highly refined lubrieating oils with has highly refined lubricatin oils, or stated in another way, mixtures of corrosive oils and non-corrosive oils, examples of the latter being lubricating oil fractions from Winkler crude or crudes of the Winkler type.

We have found that corrosivenes is inhibi and highly desirable properties are imparted to lubricating oils by adding thereto up to 1%, but preferably 0.05% to 0.75% of certain organic pmticularly aliphatic or open chain organic compmmds containing nitrogen, oxygen and/or sulfur, such as the areas the general formula n iosasz. Divided and this application September 17, 1931, serial No.

application November 2,

Urea

Phenyl urea Diethyl diphenyl urea Di alpha naphthyl urea Di-O-tolyl urea Mono-O-tolyl urea;

the thio ureas having the general formula in which R1, R2, R3 and R4 may be either hydrogen, an alkyl radical, an alkylene radical or an aryl radical such as Thio urea Di octyl thio urea Di butyl thio urea Di cetyl thio urea Ally! thio urea Phenyl thio urea Di phenyl thio urea Phenyl ailyl thio urea.

Since these compounds are subjected to high temperature conditions it is highly desirable that the compounds of the aforementioned typehaving boiling points of about 400 F. or greater-be used.

The effectiveness of compounds of the above type as corrosion inhibitors is demonstrated by the following examples in which they were subjected to one or more diiierent sets of conditions, each. of which is more severe than those encountered in the actual operation of internal combustion engines.

Method I.--Cadmium-silver alloy bearings are submerged in a highly refined oil to which the compound to be tested is added and the oil airagitated and heated to about 341 F. At regular intervals the test strips \are removed from the bath, washed free of oil and weighed to determine the loss in weight and then replaced in the bath for further testing.

Method II.By this method a highly refined oil, to which the corrosion inhibitor is to be added, is preoxidized for either 25 hours or hours by air agitating the same at about 341 F.

' The-corrosion inhibitor and the weighed ings are placed in a highly refined oil containing the inhibitor which is airgitated at about 341 F. At periodic intervals the bearings are removed from the oil bath, washed free oi oil and the low in weight determined. Each time before being replaced in the oil bath the bearings are polished bright and reweighed and again tested for predetermined periods. This method dififers from Method II in that the test is started with an unoxidized highly refined oil and the test bearings are polished at predetermined intervals.

In each of the above methods the oil used was a motor oil refined to such an extent that a loss in weight of more than 5-mg./cm. is obtained in 25 hours or less on a cadmium-silver alloy bearing submerged in an air-agitated oil at 340 F., which oil has been preoxidized for 25-50 hours at about 340 F.

In Table I are tabulated the results obtained with several representative compounds using test Method I above described.

Table I Loss in mgjcm. on m 24 hrs. 72 hrs.

Control. ll. 0 93. 5 Control-+0.05% urea 0. 0 0. 0 ControH-OJV dibutyl thiourea 0. 0 0.9 Control-$0.19 diphenyl thburea. 0. 0 17. 1 Control+0.l% thiourea 0.0 do Control-M0575 thiourea l). 0 0. 0

In Table 11 are tabulated the results obtained with representative compounds when tested ac- In Table III are the results obtained with several representative compounds when tested according to the above described test Method III.

Table III Loss in mgJcm.

Periods Oil 1st 241 3d 24 hrs. 6 hrs. 16 hrs.

Control 3. 6 5. 0 Z). 5 Control+phenyl allyl thiourea 0. l (l. 0 0. 0

While we have described in detail the use or the hereinbeiore mentioned compounds as corrosion inhibitors in "highly" refined lubricating oils. we contemplate the use of up to 10% 01 these. compounds in lubricating oils whether highly refined or not. for the purpose of improvingthefilmstrengthfliereotandto-hnpsrt to lubricants improved extreme characteristics. These compoimds may also be used to improve the lubricity and other desirable properties oi. lubricating oils.

Some of the hereinbefore named compounds may not be completely soluble in the lubricant,

. in which case efiective results are obtained by suspending the inhibitor in the lubricant by means of a small amount of a peptizing agent such as aluminum naphthenate, aluminum stearate, etc. a

We do not limit ourselves to the specific unbodiments or our invention herein described except as defined by the appended claims.

We claim:

1. A corrosion inhibited lubricating oil adapted for use in the presence of hard metal alloy bearings having the corrosive susceptibility of alloys of the class consisting of cadmium-silver, cadmium-nickel and copper-lead alloys comprising a highly refined mineral lubricating oil normally corrosive ,to such alloys and a small but sufilcient amount to inhibit the corrosion of said alloy bearings of an organic compound having the general formula in whichx is an element selected from the group consisting of oxygen and sulfur, and R1, R2, R3 and Rs are substituents selected from the group consisting of hydrogen, alkyl radicals, allqlene radicals and aryl radicals.

2. A corrosion inhibited lubricating oil adapted for use in the presence of hard metal alloy bearings of the class consisting of cadmium-silver, cadmium-nickel and copper-lead alloys which comprises a highly refined mineral lubricating oil normally corrosive to bearings of said type and an urea, said urea being added in small but sufficient amounts to inhibit the corrosion of said alloy bearings.

3. A corrosion inhibited lubricating oil as described in claim 2 in which the urea is O-tolyl urea.

4. A corrosion inhibited lubricating oil adapted for use in the presence of hard metal alloy bearings of the class consisting of cadmium-silver, cadmium-nickel and copper-lead alloys which comprises a highly refined mineral lubricating oil normally corrosive to bearings of said type having added thereto a thiourea in small but sufiicient quantities to inhibit the corrosion of said alloy bearings.

5. The method of preventing the corrosion of hard metal alloy bearings having the corrosion susceptibllity of alloys of the class consisting of cadmium-silver alloys, cadmium-nickel alloys and copper-lead alloys, by highly refined mineral lubricating oils which comprises adding to said oils normally corrosive to said alloy bearings in which X is an element selected from the group consisting of oxygen and sulfur, and R1, Ra, R: and R4 are substituents selected from the group consisting of hydrogen, alkyl radicals, alkylene radicals and aryl radicals.

6. A lubricant consisting of a mineral lubricating oil normally corrosive to alloys having the corrosive susceptibility of alloys of the class consisting of cadmium-silver alloys, cadmium-nickel alloys, and copper-lead alloys, and a hydrocarbon substituted thiourea added in amounts sufficient to render said mineral lubricating oil non-corrosive to said alloys.

7. The method of preventing the corrosion of alloy bearings having the corrosive susceptibility of alloys of the class consisting of cadmium-silver alloys, cadmium-nickel alloys, and copper-lead alloys, by highly refined mineral lubricating oils normally corrosive to said alloys which comprises adding to said oils a hydrocarbon substituted thiourea in small but corrosion inhibiting proportions.

8. A lubricant consisting of a mineral lubricating oil normally corrosive to alloys having the corrosive susceptibility of alloys of the class consisting of cadmium-silver alloys, cadmiumnickel alloys, and copper-lead alloys, and an alkyl thiourea added in amounts sufficient to render said mineral lubricating oil non-corrosive to said alloys.

9. The method of preventing the corrosion of alloy bearings having the corrosive susceptibility of alloys of the class consisting of cadmium-silver alloys, cadmium-nickel alloys, and copperlead alloys by highly refined mineral lubricating oils normally corrosive to said alloys which comprises adding to said oils an alkyl thiourea in small but corrosion inhibiting proportions.

10. A lubricant consisting of a mineral lubricating oil normally corrosive to alloys having the corrosive susceptibility of alloys of the class consisting of cadmium-silver alloys, cadmium-nickel alloys, and copper-lead alloys and thiourea added in amounts sufficient to render said mineral lubricating oil non-corrosive to said alloys.

11. The method of pre enting the corrosion of alloy bearings having the corrosive susceptibility of alloys of the class consisting of cadmiumsilver alloys, cadmium-nickel alloys, and copperlead alloys by highly refined mineral lubricating oils normally corrosive to said alloys which comprises adding to said oils thiourea in small but corrosion inhibiting proportions.

12. A lubricant as described in claim 8 in which the alkyl thiourea is dibutyl thiourea.

13. The method of preventing the corrosion of alloy bearings as described in claim 9 in which the alkyl thiourea is dibutyl thiourea.

14. The method of preventing the corrosion of alloy bearings having the corrosive susceptibility of alloys of the class consisting of cadmium-silver alloys, cadmium-nickel, alloys and copperlead alloys by highly refined mineral lubricating oils normally corrosive to said alloys, which comprises adding to said oils an urea in small but corrosion inhibiting proportions.

15. The method of preventing, the corrosion of alloy bearings as described in claim 14 in which the urea is O-tolyl urea.

16. The method of preventing the corrosion of alloy bearings having the corrosive susceptibility of alloys of the class consisting of cadmium-silver alloys, cadmium-nickel alloys and copperlead alloys by highly refined mineral lubricating oils normally corrosive to said alloys, which comprises adding to said oils a thiourea in small but corrosion inhibiting proportions.

CLARENCE M. LOANE. BERNARD H. SHOEMAKER. 

